Effects of D-D, telone or dazomet applied to potato ridges in spring on potato cyst-nematode, Heterodera rostochiensis, in sandy loam and silt loam soils.

Abstract

SUMMARYLarge amounts of dazomet (329, 439 kg/ha) applied to potato ridge soil in spring, before potatoes were planted, controlled potato cyst‐nematode (Heterodera rostochiensis) in sandy loam and silt loam more effectively than large amounts of D‐D (359, 448 kg/ha). In heavily infested sandy loam, 329 kg dazomet/ha or 857 kg methyl bromide/ha applied in spring 1969 or 439 kg dazomet/ha applied in autumn 1968, greatly decreased the number of larvae able to invade potato roots, so Majestic potatoes grew and yielded well without increasing the number of nematodes left in the soil after harvest. Large amounts of D‐D or Telone applied to the topsoil in autumn or to the ridges in spring were less effective in controlling potato cyst‐nematode or increasing potato yields. Applied in spring 1969 to silt loam ridges, 439 kg dazomet/ha had more effect than 448 kg D‐D/ha on potato cyst‐nematode and on the increase in yield of Majestic potato. The yield of Maris Piper potatoes (resistant to H. rostochiensis pathotype A) in infested silt loam was increased greatly by D‐D, as much by 112 as by 224 or 448 kg/ha.